1. Field of the Invention
The present invention pertains to the art of illumination and, more particularly, to a modular lighting system for use in connection with one or more shelves of a product display unit.
2. Discussion of the Prior Art
Utilizing lighting units to illuminate products displayed on shelves of display cabinets or the like is widely known in the art. For instance, it is common to attach one or more lighting fixtures within a refrigerated display cabinet of a supermarket in order to illuminate food products supported on vertically spaced shelves of the cabinet. Most commonly, fluorescent lighting is used for this purpose, although it has been known to utilize incandescent lighting.
Regardless of the specific type of lighting source utilized, the additional source of lighting can advantageously enhance the visibility of food products for consumers, while the lighting fixtures can also have a detrimental effect on the refrigeration system. More specifically, all types of lighting sources generate heat which is counterproductive to the refrigeration system. Typically, the lighting units are mounted to an upper cabinet panel or directly beneath shelves of the display unit to illuminate food items placed on a lower shelf. In any case, the lights will dissipate heat by convection, radiation and conduction. The heat will inherently rise and at least raise the temperature of the products displayed above the lighting source.
Since many products must be maintained within a certain temperature range in order to sustain a desired shelf life, it is also known in the art to compensate for the heat developed by the lights by increasing the level of refrigeration produced. This need for increased refrigeration will result in longer compressor running periods and/or higher capacity refrigeration systems to be incorporated into the display cabinet. In any case, the costs associated with operating the display cabinet are raised, thereby representing an additional expense for the supermarket that is typically reflected in overall product prices.
Although the use of such lighting systems has certain negative aspects, the use of these lighting systems are still deemed necessary in many environments, particularly refrigeration display cabinets. Even in the case of display units used to support other products which do not require a dedicated refrigeration system, illuminating the products may still be desirable. However, the additional heat produced can still have a detrimental effect.
Proposals have been made in the art to minimize these negative heating effects. For instance, one major reason for the switch from incandescent to fluorescent lighting fixtures was that fluorescent lighting tends to develop lower levels of heat for a given light output. However, the use of fluorescent lighting can still develop a significant amount of heat which needs to be considered in the overall design of a display unit. Regardless of the type of lighting source utilized, prior emphasis has been mainly placed on insulating a lighting source from its own housing so as to indirectly insulate a display cabinet. Such an arrangement is exemplified in U.S. Pat. No. 4,748,545. This type of arrangement fails to take into account that the light housing can be used as a direct means to evenly distribute and dissipate the developed heat.
When contemplating the retrofitting of display units which were not originally designed for use with lighting systems, consideration must be given to numerous factors, including reasonable cost constraints, sizing parameters, the manner in which heat from the lighting system will affect products stored on shelves of the display and the aesthetics of the final overall unit. In general, little emphasis has been placed in the past on retrofitting food display cabinets or the like with lighting systems. That is, new lighting systems may be designed when production is changed on a refrigerated food display cabinet, but little or no efforts have been undertaken to retrofit existing food display cabinets with more efficient lighting systems or to even add lighting systems to non-refrigerated food product displays.
Based on the above, there exists a need in the art for an improved lighting system for a food product display unit wherein the heat generated by the lighting system is efficiently, thermally isolated from displayed products. In addition, there exists a need in the art for a modular lighting system which will enable the easy retrofitting of standard food display units and that can be readily implemented in the manufacturing of new display units, while having an aesthetic design so as to be pleasing to consumers.